Automatic regulating apparatus for current supply systems



Jan. 17, 1939. 5 M HANLEY 2,144,290

AUTOMATIC- REGULATING APPARATUS FOR CURRENT SUPPLY SYSTEMS Filed Aug.26, 1935 3 Sheets-Sheet l Jan. 17, 1939. s. M. HANLEY AUTOMATICREGULATING APPARATUS FOR CURRENT SUPPLY SYSTEMS Filed Aug.- 26, 1955 3Sheets-Sheet 2 HHHHH'H s. M. HANLEY 2,144,290

AUTOMATIC REGULATING APPARATUS FOR CURRENT SUPPLY SYSTEMS Jan. 17, 1939.

Filed Aug. 26, 1935 3 Sheets-Sheet 3 l Illllt //c5' lllllllllllllllkPatented Jan. 17, 1939 UNITED STATES PATENT OFFlCE AUTOMATIC REGULATINGAPPARATUS FOR CURRENT SUPPLY SYSTEMS troit, Mich.

Application August 26, 1935, Serial No. 37,798

2 Claims.

The present invention relates to automatic regulating apparatus forcurrent supply systems. The gen ral object of the invention is toprovide an improved system and apparatus which will function in responseto different load demands on a load circuit to control automatically thevoltage impressed on the load circuit. The invention has particularapplication to rectifying systems wherein the alternating current of thesupply circuit is rectified for the load circuit, as for example inbattery charging systems and in battery eliminator systems.

lhe regulating function is performed by varying the magneticpermeability of a reactor com- 1 prising a multiple leg core structurewhich carries windings energized by alternating current and by directcurrent. Another object of the invention is to provide improved meansfor controlling the flow of the alternating current fluxes in said corestructure and for effecting an improved correlation of the fluxestherein to secure the desired control of the voltage effective on theload circuit.

The invention is of important practical utility in connection withisolated automatic telephone exchanges or any type of load whichrequires direct current for intermittent duty operation. Such a load,particularly in the case of a telephone system, may vary widely, as fromsubstantially no load during certain parts of the night to a maximum forthe busiest hours of the day or evening. A direct current supply systemunder such circumstances must accommodate itself not only to the loadbut also to the characteristics of the battery. Such isolated telephonestations have no person in attendance and only periodical inspection,as, for example, monthly, the attendant inspects the condition of thecells and supplies any necessary make-up water. For such requirements,it is necessary that the rate of recharging the battery be reduced tosuch a value that gassing is a minimum. A certain amount of gassing isdesirable to stir up the electrolyte so that it does not stratify, butany excessive gassing which would only waste water is to be avoided. Thecharacteristics of the system should therefore be such as to allow thebattery to assist in supplying the demand for peak loads, but on theother hand, the rectifier must cut in and recharge the battery as soonas peak loads are passed and then cut out or substantially ceasecharging as the battery becomes substantially fully charged. The systemof the present invention accomplishes the above and other purposes in ahighly satisfactory manner.

Other objects and advantages of the invention will appear from thefollowing detail description of certain preferred embodiments thereof.In the accompanying drawings illustrating such embodiments:-

Figure 1 is a diagrammatic view of one form of the improved apparatusand system of the invention;

Figure 2 is a diagrammatic view of the reactor of this embodiment,showing the relation of the fluxes therein during the other alternationin the alternating current supply circuit;

Figure 3 is a diagrammatic view, similar to Figure 1, showing anotherform of the invention;

Figure 4 is a typical curve showing the regulation obtainable by thislatter embodiment; and

Figure 5 is a diagrammatic view of another form of the invention.

The conductors 8 and 9 represent an alternating current supply circuitof commercial frequency. A transformer II has its primary winding l2connected to the supply circuit 8, 9. Taps are preferably provided atboth ends of the primary winding for voltage adjusting purposes. The twoend terminals of the secondary winding l3 connect with conductors l4 andI5 leading to coils [4a and l5a on the end legs of a threeleggedreactor. A center tap of the secondary winding l3 connects throughconductor 16 with a coil Ifia on the center leg of this reactor. Thereactor is designated IS in its entirety, and comprises a core structureincluding a left leg I81, 8. right leg I81, a center leg l8c, and topand bottom yokes i825 and 18b joining the ends of the three legs.

The conductor [4 continues from the other end of the coil Ma to arectifying unit 2!; and, correspondingly, the conductor I 5 continuesfrom the end of the coil a to a similar rectifying unit 22. Theserectifying units may be of the tube type or of the dry disc type. In thearrangement illustrated, I have shown these rectifiers as being of thecopper oxide type. The corresponding end terminals of these rectifyingunits are connected to a conductor 23 which represents one side of therectified current load circuit. The other side 24 of this load circuitis completed through the central coil lea and conductor l6 to themid-point of the transformer secondary l3. The load circuit'is shown asserving to charge a storage battery 26, the apparatus being ofparticular advantage in this regard for telephone exchanges, directcurrent signaling systems, etc. In this embodiment, the battery isconnected by the leads 23a. and 24a to a telephone exchange. Suchexchange may be an isolated automatic telephone exchange having noattendants and being given only periodical inspection, as, for example,once a month. It will, of course, be understood that any similar loadmay be employed instead of the telephone systern. The conductor 23 isthe positive side of the load circuit and the conductor 24 is thenegative side. A conventional ripple suppressing choke 21 is preferablyincluded in series in the load circuit. Where it is desired touse theapparatus in the capacity of a battery eliminator, the load circuit willinclude any suitable filter system, as will be later described.

Connected in shunt across the conductors I4 and I5 at a point betweenthe controlling reactor i8 and the rectifying units M, 22 is a shuntimpedance 3 I. This impedance may be inductive, capacitive, orresistive, or any combination thereof, although I preferably employ aninductive reactance, as shown. In the inductive form shown, this shuntis preferably designed so that the impedance variation therein fromno-load or light-load to full-load is approximately in the ratio of 3 to1.

The amount of alternating current fluxflowing through the central legI80 of the reactor core is arranged to be controlled by a low resistancecoil 33 mounted on the central leg. The ends of this coil are connectedto an adjustable resistance 34. Reducing the effective resistance ofsaid coil, for a greater current flow therethrough, reduces or minimizesthe flow. of alternating current flux through the central leg I80, and,conversely, increasing the effective resistance of said coil increasesthe amount of alternating current flux passing through the central leg.

I find it preferable in practice to make the two end coils I la. and I5aof substantially the same number of turns or the same resistance so thatunequal loads are not thrown upon the rectifying units 2| and 22, and sothat there will be no abnormal or irregular wave forms in the current ofthe load circuit. I also find it prefere The regulating function of thecontrol device I8 arises from the interaction of the alternating currentfluxes and the direct current fluxes in the core structure of thedevice, whereby the permeability of the structure is modified in suchmanner that its impedance is caused to vary substantially in accordancewith the demands in the load circuit. A clear understanding of theoperation of the device can best be had by making certain more or lessarbitrary distinctions between the alternating current fluxes and thedirect current fluxes. It will therefore be understood that thefollowing reference to three groups of fluxes interacting in the corestructure is more or less arbitrary for the purpose of illustration, andis not limitative of the invention. First, with reference to thealternating current fluxes, it will be noted that an alternating currentis being by-passed or shunted through the shunt impedance 3| during theentire operation of the apparatus, irrespective of the load drawn by theload circuit. This alternating current traverses both end coils Ida. andI5a, being conducted from one coil to the other through the shuntimpedance 3 I. The two coils are so wound that the alternating currentfluxes created by this alternating current circulate in the samedirection through the outer portions of the core structure, disregardingfor the moment the circulation of these fluxes through the center leg.This alternating current flux is denoted by the wavy arrows m. Thus,during the alternation or half-cycle illustrated in Figure 1 when thealternating current is passing downwardlythrough the left end coil Maand upwardly through the right end coil I500, the alternating currentflux a: is passing downwardly in the left leg I8! and is passingupwardly in the right leg I81. Conversely, during the next alternationor half cycle illustrated in Figure 2, when the alternating current ispassing downwardly through right coil I50. and upwardly through leftcoil Ma, the alternating current flux is passing downwardly in the rightcore leg and is passing upwardly in the left core leg. The foregoingreference to the alternating current flux passing upwardly or downwardlythrough one end leg corresponding to the flow of the alternating currentupwardly or downwardly through the coil on that leg is purely arbitraryfor facility of description, and in practice the reverse of this mayfollow from a reversed relation of the two end windings.

Referring now to the direct current fluxes set up by the two end coils,it will be evident that during the alternation illustrated in Figure 1there is a component of direct current passing down through the leftcoil Ma and down through the rectifier unit 2I to the load circuit. Thisdirect current component flowing through said winding sets up a fluxwhich may be referred to as a direct current flux. Similarly, during theother alternation illustrated in Figure 2, there is a component ofdirect current passing down through the right coil I5a and through therectifying unit 22 to the load circuit. This direct current componentlikewise sets up what may be termed a direct current flux in the corestructure. These direct current fluxes set up in each case by the twoend coils are denoted by the solid straight arrows y.

Referring now to the flux which is created by the direct current flowingthrough the central coil Isa, this flux is unidirectional at all timesthrough the central leg I80 of the core structure,

and is denoted by the dotted straight arrows z. The central coil is sowound that the direct current flux 2 created thereby flows in adirection which is additive with respect to the direct current flux y inone end leg and which is subtractive with respect to the alternatingcurrent flux a: in the other end leg. For example, during the half cycleillustrated in Figure 1, the direct current flux 2 is additive withrespect to the direct current flux y in theleft leg I81, and issubtractive with respect to the alternating current flux 9: in the rightleg I81. Conversely, during the alternation illustrated in Figure 2, thedirect current flux a is additive with respect to the direct currentflux y in the right leg I81 and is subtractive with respect to thealternating current flux m in left leg I81.

It will be seen that the value of the alternating current flux at isrelatively constant throughout the entire operation of the apparatus,being dependent upon the value of the shunt impedance 3| and being moreor less independent of changing load demands in the load circuit. Thisalternating current flux serves to establish or maintain a desired fluxdensity in the core structure. As previously remarked, the amount ofthis alternating current flux which is allowed to travel through thecentral leg ||lc of the core can be adjusted by adjusting the resistance34 in order to change the choke value of the coil 33. The direct currentfluxes y and a, on the other hand, are directly subject to the demandsof the load circuit. This will be obvious from the fact that anincreased current flow in the load circuit necessarily involves the flowof increased direct current components alternatively in the two endcoils and the flow of a larger unidirectional current'in the centralcoil |6a. Hence, it will be seen that as the current in the load circuitincreases, the direct current fluxes y and 2 act cumulatively in thecore structure to increase the flux density in the end legs of the core,this increase of flux density lowering the effective permeability ofthose portions of the core structure directly within the two alternatingcurrent coils Ma and |5a and decreasing the impedance in these coils.That is to say, during the alternation illustrated in Figure 1, thepermeability of the left leg IBZ of the core structure is reduced, andduring the alternation illustrated in Figure 2 the permeability of theright leg I81 is reduced. The

decreased impedance of the coils on these legs means the transmission ofa higher potential to the load circuit, or a compensation for some orall of the drop of potential which would ordinarily result from thehigher current flow in the load circuit.

For'the purpose of reducing the induced alternating current component incentral coil |6a, resistor 34 should be set for the lowest effectiveexternal resistance which will give the desired performance curve. Inmany applications, resistor 34 is replaced by a short circuiting jumper.

Coil 33 and associated resistor 34 or shorting jumper tend to keep thefiux through leg |8c at a constant value. When coil |6a is omittedas incertain applications of low impedance rectiflers-coil 33 and associatedjumper keep the remanent direct current induction at a considerablyhigher value. This higher value of direct current induction holds thealternating current permeability of the structure lower with a resultanthigher voltage for the rectifier elements and a higher load voltage fora given current.

In Figure 3 I have shown a modified arrangement wherein electronic tubes4| and 42 are employed as the rectifying units. These tubes arepreferably of the low impedance type, such as Tungar tubes. The cathodesof these tubes may be energized from any separate source of currentsupply, or may be energized from small secondary windings 43 and 44 onthe power transformer The conductor 4 leading from alternating currentcoil |4a is connected to the anode of its associated tube 4|, and theconductor l5 extending from the other alternating current coil |5a isconnected to the anode of its associated tube 42. The shunt impedance 3|is connected across the conductors l4 and I5 below the alternatingcurrent coils, as before described. The two cathodes of the rectifiertubes are connected to each other by a conductor 23', from which oneside 23 of the load circuit extends. The appara tus may be employed as abattery charger with the load circuit connected to a storage battery, asdescribed of the preceding embodiment; or the apparatus may be employedas a battery eliminator. As illustrative of the latter, I have shown aconventional filter system 48 in the load circuit for supplying. anon-pulsating direct current to any suitable load, represented at 5|.Preferably, a bleeder load, such as a high resistance 52, is connectedacross the load circuit for maintaining a small load through the circuitwhen no current is being drawn by the device 5|. For the purpose offacilitating the explanation of the curves of Figure 4, I have shown adouble pole, double throw switch 53 connected with conductors l6 and 24and with the direct current coil I6a. When the switch is in position 531the coil |6a is included in circuit and when the switch is in position531 the coil is out of circuit.

The curves shown in Figure 4 were taken on a rectifier and filter systemwith Tungar type rectifier tubes. The primary voltage of the transformerwas constant during the test. The taps on the transformer primary |2,turns on the coils I465, |5a, turns on shunt impedance 3|, and value ofbleeder load were not changed during this test.

Curve C was taken with a jumper across coil 33 and with coil |Gaconnected to produce a flux 2 which aided the fluxes y produced by coilsMa and H511.

Curve C was taken with a jumper across coil 33, and with the switch 53in position 531, or no direct current turns on center leg |8c.

Curve C was taken with center leg |8c free of windings, i. e., theresistor 34 was open-circuited and the switch 53 was in position 531.

Curve C was taken with a jumper across coil 33 and with the switch 53 inposition 531*, but with coil Ilia. connected to produce a flux 2 whichopposed the fluxes y produced by coils Na and A comparison of curves Cand C will show the gain in overall performance by having the coil |6 onleg I80. For certain applications a curve similar to C is more desirablethan C For other applications a curve which would fall between thelimits of C and C would be desirable. Curve C has approximately the sameslope and shape as a rectifier filter system which has no compensationfor load.

A comparison of curve C and curve C shows the effect of the directcurrent flux z in the core structure. Curve shows the effect when theflux z aids the other direct current flux y, and curve C shows theeffect when the flux z opposes the flux 1/.

In Figure I have shown a modified construction using two core structuresas the regulating reactor, which core structures are separatedmagnetically but are connected in parallel relation electrically. Thetwo core structures 8 and 2! are preferably of the three-legged type,although other forms of closed core structures can be used in thisembodiment. One alternating current coil 4:1 is wound on the center leg||8c of the core H8, and the other alternating current coil ||5a iswound on the center leg 2|8c of the other core 2| 8. These twoalternating current coils are connected between the outside terminals ofthe transformer secondary l3 and the rectifying units 2| and 22,substantially as previously described. The shunt impedance 3| isconnected across the two rectifying units, also as previously described.

The direct current coil is separated into two sections H611 and 2|6a,both mounted on the center legs of the core structures and bothconnected in series with each other and with the load circuit 23, 24.

The choke coil is likewise separated into two sections I33 and 233, bothmounted on the cen ter legs of the core structures and both connected inseries with each other and .withthe adjustable resistor I34. Adjustingthe resistance 134 varies the current in both coils and varies theamount of coupling between the two Structures. In other respects, thecircuit arrangement is like that shown in Figure 1.

The same general theory of operation previously described applies tothis embodiment, with the possible exception that the twoshort-circuited coils or choke coils I33 and 233 perform a couplingfunction in this embodiment, as well as the function previouslydescribed. This embodiment may also be used as a battery eliminator.

In each of the above described embodiments, the point of intermediatepotential for conductor '16 can be obtained by the use of anauto-transformer or possiblyby the use of a resistor, instead of by thecenter tap on the transformer secondary 13. In this regard, an exactrelation of center tap or. mid-point is not essential; either end of thesecondary 13 can produce a higher voltage than the other end. That is tosay, an unbalanced relation of voltages is operative and practical wherethere'is no objection to an uneven Wave form in the load circuit, orwhere a. sumcient degree of filtering action is present in the loadcircuit to smooth out an uneven wave form.

While I have illustrated and described what I regard to be the preferredembodiments of my invention,'nevertheless it will be understood thatsuch are merely exemplary and that numerous modifications andrearrangements may be made therein without departing from the essence ofthe invention.

I claim:

1. Incombination, an alternating current supply circuit, a directcurrent load circuit, rectifying means through which current is fed fromsaid supply circuit to said load circuit and regulating apparatusresponsive to the load'in said load circuit for varying the impedance'ofsaid supply circuit, said regulating apparatus comprising two magneticcore structures, alternating current coils on said core structuresenergized by the alternating current of said supply circuit and bycomponents of the current fed to said load circuit, direct current coilson said core structures connected in series with each other and with theload circuit, and choke coils on said core structures establishing acoupled relation between said core structures and controlling thepermeability thereof.

2. In combination, an alternating current supply circuit, a directcurrent load circuit, rectifying means through which current is fed fromsaid supply circuit to said load circuit and regulating apparatusresponsive to the load in said load circuit for varying the impedance ofsaid supply circuit, said regulating apparatus comprising two magneticcore structures, alternating current coils on said core structuresenergized alternatively by components of the current fed to said loadcircuit, a shunt impedance connecting said coils for causing them to beenergized by the alternating current of said supply circuit, directcurrent coils on said core structures'connected in series with eachother and with the load circuit, and choke coils on said core structuresestablishing a coupled relation between said core structures andcontrolling the permeability thereof.

STANLEY M. HANLEY.

